Weight training typically involves the use of barbells and dumbells. Both may consist of solid bars with opposite ends mounting removable weight training plates. The plates are supplied in sets with various weight increments of, for example 2.5 lbs. Thus, a dumbell weighing 25 lbs. (discounting the weight of the bar) might consist of two 10 lb. plates and two 2.5 lb. plates mounted at opposite ends of the bar. Additional plates must be added if the user wants to increase the amount of weight on the bar. Changing the weight to, say, 40 lbs. requires more or heavier plates. Two 2.5 lb. plates and two 5 lb. plates could be added to the existing plates to produce a total weight of 40 lbs. Alternatively, a total of four 10 lb. weights or eight 5 lb. plates could be used. This example is given merely to indicate the need for many weight training plates for even a single dumbell. Some routines require two dumbells of equal weight used simultaneously. Usually, the number of plates grows with the development of the user's muscles. Additional plates are thus continually being added to the original "set ".
Weight training plates are both expensive and cumbersome to store, due to their size and weight. It is therefore desirable to increase the capability of an existing weight set without substantially increasing the number of weight training plates required.
The amount of weight on a bar can be increased by extending the mass of the weight beyond the arms of the user. A typical example is the "swingbell". The swingbell consists of a bar having a set of weights mounted at one end. The free end of the bar is grasped at the other end. The mass of the weight thus extends outward from the user's arm. The relationship of weight and distance from the hand increases the leverage of the weight against the user's arms. The increase is a factor of the distance between the user's palm and the center of mass for the weights. A device similar to a swingbell is shown in U.S. Pat. No. 1,658,108.
Swingbells require sufficient strength at the wrist to support the cantilevered weight. The wrist muscles are normally substantially weaker than the upper arm muscles. Thus, "swingbells" are ineffective for training to develop muscle groups other than those in the wrist area.
U.S. Pat. No. 4,312,506 to Brennan discloses a bicep excerising curling bar that reduces wrist fatigue during curling operations. However, this apparatus functions to orient the mass of the weight on the dumbell or barbell inward, toward the user's body from the hands. The lever arm is therefore reduced. The overall effect of the weight training plates mounted to the bar is correspondingly reduced.
U.S. Pat. No. 4,231,569 to Rae discloses a device that is used to extend a standard bar or dumbell weight outwardly of the user's forearm to increase the leverage produced by the weight. This device includes a triangular framework having the weight, a handgrip, and a forearm brace at corners of the triangle configuration. The user's forearm will come into contact with the brace only through certain portions of arcuate movement of the user's arm. The weights swing freely through the remainder of arm motion with the forearm brace disengaged from the user's forearm. The effect with the weight hanging freely is no different than the effect experienced with ordinary dumbells.
The above cited patents are illustrative of apparatus used in conjunction with weight training plates for engagement of some sort with the user's forearm. The reason for forearm engagement by a pad in the Brennan patent is to eliminate strain at the user's wrist. Forearm engagement by the Rae device is intended to increase resistance of existing weights at specified angular orientations of the user's forearms to the upper arms. There is a continuing need, however, to obtain some form of exercise device that will effectively increase the distance between the weight and elbow and that will maintain the leverage produced thereby continuously during exercising. Such a device would reduce the need for continually adding plates to an existing set.